I took the opportunity of adding some functionality to my spreadsheet. Now it also calculates the "0.1" point and automatically shows the correct placement of the ASA triangle on the grid. The user can easily determine if the data passes through the red circle or not. In this case you can see that it does pass through the red circle (1.2 log out from the speed point and 0.8 log up from the speed point).
So the spreadsheet automatically calculated the 0.1 point as 3.11. How does that compare with what you got by hand?

The 0.1 point is the GREEN CIRCLE and the ASA/ISO speed point is the GREEN TRIANGLE. To save weeks of programming I did NOT use a spline. I used linear interpolation. As you can see it is as good as one could eyeball it on graph paper. I'm happy with it.
The WHITE TRIANGLE is the W-speed point with the safety factor added (surrogate for 0.3G point with one stop safety factor). Delta-X plus safety factor would likely be similar. For educational purposes, I guess the next step is to program the Delta-X into the spread sheet....

Last edited by ic-racer; 07-22-2012 at 05:51 PM. Click to view previous post history.